Nocturnal Foraging by Ants at a Sandstone Bee Nest Aggregation (Hymenoptera: Apidae and Formicidae)

Ants are immensely important predators in terrestrial ecosystems but surprisingly little is reported on their role in bee predation. Here, we describe the ant Pogonomyrmex subnitidus Emery, 1895 foraging at a bee nest aggregation in Utah. Many instances were observed of P. subnitidus, and another ant, Pheidole clydeiGregg, 1950, scavenging on the nests of the recently-described bee Anthophora puebloOrr, 2016, which nests in sandstone. One worker ant of P. subnitidus was also observed taking a live bee larva back to its nest, indicating that the ants occasionally act as predators. The existence of nocturnal foraging in P. subntidus demonstrates greater temporal foraging plasticity than prior reports of bimodal foraging strategy during the day. Potential drivers of this behavior and the relation of these two new ant associates to the bees are discussed.